The tool itself is a nice Ruby on Rails application (includes pink fade effects! yellow is so 2006) that gives you a visual canvas to play with your mind.

Their approach to offline is similar to Google Reader in that the user has to say “hey, take me offline”. The interface to that is a nice little slider widget. At the point your maps are sync’d down to the local store.

I would love to see it auto sync, and I noticed a couple of issues when I actually went offline but didn’t tell the tool first (would be nice to have the tool grok that) but the mind map tool in general is a nice app to use. It feels like Geni.

Another tool which I really likes was comapping.com. It has some form of offline mode when you loose internet connection. Regardless, I prefer the structure and format of comapping as compared to existing tools